After Beatrice is seized by Inquisitors in Genoa, she is imprisoned at Lucca (331). Euthanasia petitions Castuccio for Beatrice’s release, and Castruccio grants it (336-8). After her release, Beatrice is brought to the palace that is given to Euthanasia after Valperga is destroyed.
The narrator gives very little detail on these specific locations within Lucca, and this has the effect of blurring them, making the entire city of Lucca into a sort of prison for both Beatrice and Euthanasia. For example, as Euthanasia first approaches her Lucca palace, Shelley narrates, “She took no notice of the streets through which she passed, and cared little whether they conducted her to a palace or to a prison” (315). Similarly, the description of Euthanasia’s journey from her palace to the Lucca prison is hazy; Shelley uses images of melting and slush to make the boundary between the two locations murky and indistinct: “Euthanasia ... followed the man through the dark, wet streets of Lucca: the thaw had not yet completed its work; the snow was deep and miry under their feet; while the melting collections of several days dripped, or rather streamed from the house-roofs on their heads: the Libeccio blew a warm, cloud-bringing wind, that made the night so black, that they could not avoid the standing pools. At length they arrived at the prison; the jailor entered by a small, low door which he carefully closed after them, and then struck a light. He led Euthanasia through the bare and mildewed vaults, sometimes unlocking a massy gate, drawing back the harsh bolts which grated with rust and damp; sometimes they emerged into a passage open to the sky, but narrow, with tall black vaults about it, which dropt their melted snow and a continual and sullen splash upon the pavement” (332). Compare this with the narrator’s later decription of Euthanasia’s view from her palace tower of “narrow, deep streets of Lucca,” which “lay like the allies [alleys] of a prison around her,” and from which she longs to “fly for ever” (416-17).

Lucca: Via Fillungo view from the Clock Tower